TY - JOUR
T1 - Millimetre-long transport of photogenerated carriers in topological insulators
AU - Hou, Yasen
AU - Wang, Rui
AU - Xiao, Rui
AU - McClintock, Luke
AU - Clark Travaglini, Henry
AU - Paulus Francia, John
AU - Fetsch, Harry
AU - Erten, Onur
AU - Savrasov, Sergey Y.
AU - Wang, Baigeng
AU - Rossi, Antonio
AU - Vishik, Inna
AU - Rotenberg, Eli
AU - Yu, Dong
N1 - Funding Information:
This work was supported by National Science Foundation Grant DMR-1838532 and DMR-1710737. S.Y.S. was supported by National Science Foundation Grant DMR-1832728. This research used the Molecular Foundry and the Advanced Light Source, which are US Department of Energy Office of Science User Facilities under Contract No. DE-AC02-05CH11231. H.F. acknowledges the US National Science Foundation Research Experiences for Undergraduates (REU) programme under Grant No. PHY-1560482. We acknowledge Alex Weber-Bargioni, Edward Bernard and Hans Bechtel at the Molecular Foundry for the assistance on optical measurements.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi2-xSbxSe3 nanoribbons. The photocurrent distributions are independent of electric field, indicating that photoexcited electrons and holes form excitons. Remarkably, these excitons can transport over hundreds of micrometers along the topological insulator (TI) nanoribbons before recombination at up to 40 K. The macroscopic transport distance, combined with short carrier lifetime obtained from transient photocurrent measurements, indicates an exciton diffusion coefficient at least 36 m2 s−1, which corresponds to a mobility of 6 × 104 m2 V−1 s−1 at 7 K and is four order of magnitude higher than the value reported for free carriers in TIs. The observation of highly dissipationless exciton transport implies the formation of superfluid-like exciton condensate at the surface of TIs.
AB - Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi2-xSbxSe3 nanoribbons. The photocurrent distributions are independent of electric field, indicating that photoexcited electrons and holes form excitons. Remarkably, these excitons can transport over hundreds of micrometers along the topological insulator (TI) nanoribbons before recombination at up to 40 K. The macroscopic transport distance, combined with short carrier lifetime obtained from transient photocurrent measurements, indicates an exciton diffusion coefficient at least 36 m2 s−1, which corresponds to a mobility of 6 × 104 m2 V−1 s−1 at 7 K and is four order of magnitude higher than the value reported for free carriers in TIs. The observation of highly dissipationless exciton transport implies the formation of superfluid-like exciton condensate at the surface of TIs.
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U2 - 10.1038/s41467-019-13711-3
DO - 10.1038/s41467-019-13711-3
M3 - Article
C2 - 31844140
AN - SCOPUS:85076626393
SN - 2041-1723
VL - 10
JO - Nature communications
JF - Nature communications
IS - 1
M1 - 5723
ER -